THERMAL ENERGY STORAGE IS USEFUL IN SHIFTING ELECTRICAL LOADFROM PERIODS OF PEAK POWER TO OFF-PEAK PERIODS. THERMAL ENERGY STORAGE SYSTEMS USING COMPLEX COMPOUNDS HAVE HIGHER STORAGE DENSITIES (BOTH MASS AND VOLUMETRIC DENSITY) THAN CONVENTIONAL SYSTEMS. IN THIS PROJECT, A THERMAL ENERGY STORAGE CONCEPT IS ADVANCED TO HEAT WATER FOR DOMESTIC AND COMMERCIAL APPLICATIONS. SEVERAL METHODS EXIST FOR USING COMPLEX COMPOUNDS AS HEAT STORAGE MEDIA. TWO OF THE MOST PROMISING METHODS ARE BEING INVESTIGATED AND COMPARED IN THIS PHASE I EFFORT. THE FIRST METHOD USES TWO COMPLEX COMPOUNDS WITH SIGNIFICANTLY DIFFERENT SORPTION ENERGIES AS LATENT PASSIVE STORAGE. THE SECOND METHOD FUNCTIONS AS A HEAT-ACTIVATED HEAT PUMP WITH CYCLE TIME DURATION BEING EQUAL TO THE STORAGE WINDOW, THUS PROVIDING LATENT HEAT STORAGE IN AN ACTIVE MODE. THE CHARGING OF COMPLEX COMPOUNDS TAKES PLACE DURING OFF-PEAK HOURS BY DESORBING AMMONIA. DURING ON-PEAK HOURS, AMMONIA IS ABSORBED TO PROVIDE HEAT FOR HEATING WATER. THE PURPOSE OF THIS PROJECTIS TO DEMONSTRATE THE FEASIBILITY OF WATER HEATING SYSTEMS USING COMPLEX COMPOUNDS. EVALUATION CRITERIA WILL BE (1) PROOF-OF-PRINCIPLE EXPERIMENTS AND (2) ECONOMIC ANALYSIS, WHERE COST AND PAYBACK PERIODS ARE ESTIMATED AND COMPARED WITH OTHER EXISTING TECHNOLOGIES.